(1) Field of the Invention
This invention relates to the use of an ion implantation beam of P2+ ions or As2+ ions to dope N type shallow junction source/drain regions or gate electrodes used in devices with shallow source/drain regions. Use of the P2+ ions or As2+ ions uses lower ion density and higher beam energy resulting in improved throughput and ion source life.
(2) Description of the Related Art
As junctions become very shallow the use of P+ ion beams or As+ ion beams becomes a problem because beam energies must be kept very low while the beam ion densities must be kept very high. These requirements leads to reduced ion source life and reduced wafer throughput. This invention overcomes this problem using P2+ ion beams or As2+ ion beams.
U.S. Pat. No. 5,155,369 to Current describes a method of using two doses of ions in an ion beam to provide implantation for shallow junction devices. A first dose of ions is implanted to produce a damaged layer through which a second dose of ions is directed. The damaged layer scatters the second dose of ions and channeling is avoided.
In their book “Silicon Processing for the VLSI Era, Volume I”, by Wolf and Tauber, Lattice Press, 1990, page 327, Wolf and Tauber discuss ion implantation using doubly charged species.